Optimization of the Application of BNCT to Undifferentiated Thyroid Cancer.

DAGROSA, MA; THOMASZ, L; LONGHINO, J; PERONA, M; CALZETTA, O; BLAUMANN, H; JIMÉNEZ REBAGLIATI, R; CABRINI, R; KAHL, SB; JUVENAL, GJ; PISAREV, MA

Takamatsu, Kagawa, Japan

Congreso; 12th International Congress on Neutron Capture Therapy; 2006

International Society for Neutron Capture Therapy

Purpose: We analyzed the possible increase in BNCT efficacy by using BPA plus BOPP and the use of nicotinamide (NA) as a radiosensitizer on BNCT reaction. Materials and Methods: Nude mice were transplanted with the ARO cells and after 14 days they were treated as follows: 1) Control; 2) NCT (neutrons alone); 3) NCT plus NA (100 mg/Kg b.w/day for 3 days); 4) BPA (350 mg/kg bw) + neutrons; 5) BPA+ NA+ neutrons; 6) BPA+ BOPP (60 mg/kg bw) + neutrons. The flux of hiperthermal neutrons was 2.8 108 during 85 min. Tumor growth was measured during.30 days. Organic hidroperoxydes and caspase 3 activity were determined in the tumor at 1 and 7 days after irradiation. Mice were sacrificed at different times and the histology of the tumor was examined. Results: control mice showed a continuous tumor growth. Neutrons alone or with NA caused some delay, while in the BPA, BPA+NA and BPA+BOPP groups a 100% halt of tumor growth was observed. When the initial tumor volume was 50 mm3 or less a complete cure was found in 2/2 BPA+NA; 1/4 BPA; 7/7 BPA+BOPP. After 90 days of complete regression, recurrence of tumor was observed in 2/2 BPA/NA and 1/7 BPA+BOPP. Caspase 3 activity was increased in BPA+NA (p<0.05 vs controls) and organic peroxides were increased in groups NA+ neutrons and NA+BPA. Conclusions: a) NA increased organic peroxides generation; b) NA+BPA increased tumor apoptosis. c) Only the combination of BPA+BOPP increased significantly BNCT efficiency.